Update: Warrior and Other News

[Doug97]

Originally Posted by NikovK

I was always under the assumption that tracers didn't burn evenly, so while the bullet spins along its flightpath the glowing gas is slung off to one side, making a corkscrew effect which looks like a side-to-side wobble at an angle.

HEAT rounds penetrate by concentrating energy on one point. Spinning would slew the plasma out to the sides of the axis of spin.

I think you overestimate the speed of spin vs. the speed at which the 'jet' forms ...

[NikovK]

Well, when you're trying to put ten pounds of HE on dime, little bits matter. Its not my opinion, its a source I picked up.

"Mats Persson" <[email protected]> wrote in message
news:[email protected]...
> Karl Vorwerk wrote:
> >
> > This made me wonder. What is the spin rate (RPM) of the average rifled
tank
> > round? More interestingly how fast must it rotate to disperse the shaped
> > charges jet?
>
> spin = (muzzle velocity)/(length of one twist) [ /s]
>
> For an S-tank firing HE-shells that makes
>
> 680 [m/s] / (18*0.105) [m] = 360 [ /s] = 21600 [rpm]
>
>
> The Swedish Army noted that the 84 mm m/48 Carl Gustaf RCL had pour
> armour penetration using spin stabilized HEAT-ammunition. In 1956 they
> went to non-rotating HEAT which increased the performance.
>
> With a muzzle velocity of approximately 300 m/s and one twist in 3.268
> metres the grenade from a m/48 has a spin of 300/3.268=90 [ /s] = 5400
> [rpm]
>
> Which is notably less than the spin of a shell from a tank-gun.
>

[NikovK]

Regarding rifled vrs smoothbore...

Eugene Griessel wrote:
>
> "Zonie! remove the excitation mark and 1 M for real email address"
> <[email protected]> wrote:
>
> >The M1A1 Abrams converted to a smooth bore from a smaller rifled bore.
> >
> >What advantages does a smooth bore give you?
>
> The main ammunition for anti-tank work is an armour piercing fin
> stabilised discarding sabot round. The so-called "long-rod"
> penetrator. While spinning a shell helps to stabilise it it does
> subject the round to precession. This means the point tends to wander
> in a small circle. This is less than desirable when you want to punch
> a hole through armour by brute force. You want a "square" hit so that
> all the force is concentrated on one spot.

Also, with a need for higher velocities to penetrate armour the fin
stabilized long-rod can be accelerated to higher velocities from a
smooth bore than a rifled gun.

The gas seal on a rifled round has to be metal-on-metal contact between
the round and the barrel this has a high friction co-efficient -
limiting acceleration of the rifled round - possibly why a longer barrel
allows higher velocity (but it has an upper limit where gas pressure is
no longer able to accelerate against the friction).

On a fin-stabilized round the gas seal can be plastic etc (any suitable
low friction material). There are no edges inside the barrel to inhibit
acceleration (rifling). So more energy is expended accelerating the
round (than equivalent rifled round) allowing higher velocities from a
shorter barrel.

Advantages (IMO):
1) Cheaper barrels (no rifling)
2) Longer lasting barrels (no rifling to wear)
3) Shorter barrels (see 1 above)
4) Higher projectile velocities - better armour penetration (from
shorter barrels).
5) etc
</XMP>

For more information go here...

http://www.ciar.org/ttk/mbt/

[Mad Max]

Put it this way. If CHARM and rifled barrels are so crappy compared to smoothbore... how could it destroy another Challenger 2 in one hit? Which is the most heavily armoured tank in the NATO aresenal? They're more than capable of destroying heavy armour in one shot so what's the problem? And like I've said several times before, they're just cheaper and easier to make (smoothmore). We don't tend to care for cutting corners if it means we get better equipment.

[NikovK]

You wouldn't be blowing up NATO tanks. You'd be blowing up Kontakt-5 armored T-90s if anything. That little bit of orbit on a tungsten penetrator and the lower muzzle velocity from a rifled barrel could well make all the difference. A marginally higher velocity DU penetrator rod without a point orbit may be enough extra for the kill.

[Doug97]

Originally Posted by Mad Max

Put it this way. If CHARM and rifled barrels are so crappy compared to smoothbore... how could it destroy another Challenger 2 in one hit? Which is the most heavily armoured tank in the NATO aresenal? They're more than capable of destroying heavy armour in one shot so what's the problem? And like I've said several times before, they're just cheaper and easier to make (smoothmore). We don't tend to care for cutting corners if it means we get better equipment.

Are there any sources that mention where on the Challenger it was hit?

[Doug97]

Originally Posted by NikovK

> spin = (muzzle velocity)/(length of one twist) [ /s]
>
> For an S-tank firing HE-shells that makes
>
> 680 [m/s] / (18*0.105) [m] = 360 [ /s] = 21600 [rpm].

Where do you get the (18*0.105) bit from?

Also, isn't there some 'slippage', i.e. the round does not spin as fast as the rifling would suggest because of inertia?

BTW I don't disbelieve what you're saying, I'm just interested ...

Originally Posted by NikovK

You wouldn't be blowing up NATO tanks. You'd be blowing up Kontakt-5 armored T-90s if anything.

Are they really better armoured than the Dorchester armour of a Challenger II?

[NikovK]

Check the source. That's not my page, sorry. Regarding Dorchester/Kontakt-5, you'd be better off asking a philosopher.

I really doubt Rheinmetall is "cutting corners" on its 120mm smoothbores, just like I really doubt the USA is cutting corners by buying cheap weapons for a very expensive tank.

[Xeon]

I believe it's something like 5kph slower than the Abrams, but then they do have jet turbine engines running on aviation fuel whilst the CR2 uses diesel most of the time).

What do you mean by challenger 2 tanks run on diesel most of the time?

[Doug97]

Originally Posted by Xeon

What do you mean by challenger 2 tanks run on diesel most of the time?

I think it means that the tank uses diesel fuel to power its engine less than 100% but greater than 50% of the total time the tank is running.

Pretty confusing, I know ...